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How to Select the Right Electric Actuator Based on Force Requirements

2025-06-12
Selecting the correct electric actuator for your application is a critical decision that directly affects system performance, reliability, and operational efficiency. One of the most important factors in this selection process is understanding and matching the force or torque requirements of the load to the capabilities of the actuator.

Unlike pneumatic actuators, which are often defined by their operating pressure (e.g., 60–100 psi), electric actuators are characterized by their ability to generate linear force (in Newtons or kgf) or rotational torque (in Nm). Misjudging these values can lead to underperformance, mechanical failure, excessive wear, or even safety hazards.

VALEN TECH will explore the key steps, technical considerations, and best practices for selecting the right electric actuator based on force requirements — from basic principles to real-world applications.

What Type of Motion Does Your Application Require?

Before diving into force calculations, determine whether your application requires linear motion, rotary motion, or both.

A. Linear Motion Applications

  • Use linear electric actuators
  • Examples: gate control, valve stem operation, lifting platforms, conveyor gates
  • Measured in force (N or kgf)

B. Rotary Motion Applications

  • Use rotary electric actuators
  • Examples: ball valves, butterfly valves, dampers, rotary tables
  • Measured in torque (Nm or lb-ft)

Identifying the motion type helps narrow down the actuator category and simplifies the sizing process.

How Do You Calculate the Required Force or Torque?

Accurately calculating the required force or torque is essential for proper actuator selection.

A. For Linear Actuators:

The formula for required force is:

{Required Force} ={Load Weight}times {Coefficient of Friction} +{Acceleration Force} 

Where:

  • Load Weight is the actual weight being moved.
  • Coefficient of Friction (μ) depends on the guide system (e.g., slides, rails).
  • Acceleration Force accounts for dynamic movement.

Example:

To move a 500 kg load with a friction coefficient of 0.2 and an acceleration factor of 1 m/s²:

{Force} = (500 ,{kg} times 9.81 , {m/s}^2) times 0.2 + (500 , text{kg} times 1 , {m/s}^2) = ~1480 , {N}

So, you would need a linear actuator capable of delivering at least 1,500 N of force, with a safety margin included.

B. For Rotary Actuators:

Torque is calculated as:

{Torque (T)} = {Force (F)} times{Distance from Pivot (r)} 

Where:

  • Force is the resistance offered by the load.
  • Distance from pivot is the lever arm length.

Example:

A butterfly valve requires 300 Nm of torque to open fully. You should select an actuator rated for at least 400 Nm to account for friction, wear, and future load increases.

Should You Consider Static vs. Dynamic Load Conditions?

Yes. Different types of loads place varying demands on an actuator. Understanding these helps avoid premature failures or over-engineering.

A. Static vs. Dynamic Loads

  • Static Load: The actuator holds a position without movement (e.g., holding a gate closed).
  • Dynamic Load: The actuator must overcome inertia and friction during motion (e.g., opening a valve).

Always size for dynamic loads, especially when high start-up torque is needed.

B. Axial vs. Radial Loads

  • Axial Load: Force acting along the axis of motion (ideal for linear actuators).
  • Radial Load: Force perpendicular to the axis (can cause bending stress; may require additional support).

Rotary actuators also face side loading, which can affect bearing life and motor strain.

Are Axial and Radial Loads Impacting Your Selection?

Environmental conditions significantly impact actuator performance and longevity.

A. Temperature Extremes

  • High temperatures reduce motor efficiency and lubrication effectiveness.
  • Low temperatures can stiffen gears and seals, increasing torque requirements.

B. Dust, Moisture, and Corrosive Environments

  • Choose actuators with appropriate IP ratings (e.g., IP67 for water and dust protection).
  • Stainless steel or coated housings may be necessary in chemical plants or offshore installations.

C. Vibration and Shock

  • Industrial environments like mining or heavy machinery may require shock-resistant mounting and reinforced internal components.

What About Duty Cycle and Frequency of Operation?

The duty cycle refers to how often and how long the actuator operates within a given period.

A. Continuous vs. Intermittent Duty

  • Continuous Duty: Actuator runs for extended periods without cooling downtime.
  • Intermittent Duty: Short bursts of operation followed by cooling periods.

Actuators rated for continuous use typically have better thermal management systems and higher service life.

B. Cycle Frequency

  • High-frequency applications (e.g., packaging lines) demand actuators with high-speed motors and robust gearboxes.
  • Low-frequency applications (e.g., emergency shut-off valves) may prioritize torque over speed.

Which Voltage and Control System Is Best for Your Setup?

Electric actuators come in various voltage configurations:

  • Low Voltage DC (12V, 24V) – Common in mobile and battery-powered applications.
  • Standard AC (110V, 230V) – Suitable for industrial settings.
  • High Voltage AC (400V–480V) – Used in heavy-duty automation and large-scale infrastructure.

Also consider:

  • Control signals: Analog (4–20mA), digital (Modbus, Profibus), or wireless protocols.
  • Feedback options: Position encoders, limit switches, torque sensors.
  • Fail-safe mechanisms: Spring return, emergency override, power loss memory.

Should You Go for Smart or Basic Actuators?

Modern electric actuators range from simple on/off models to smart actuators with integrated intelligence.

A. Basic Actuators

  • On/Off control
  • Fixed travel limits
  • Manual override

Suitable for straightforward applications where cost is a priority.

B. Smart Actuators

  • Real-time diagnostics
  • Remote monitoring
  • Adaptive control algorithms
  • Predictive maintenance alerts

Ideal for critical infrastructure such as oil pipelines, power plants, and pharmaceutical facilities.

Why Apply Safety Margins and Overload Protection?

Never operate an actuator at its maximum rated capacity continuously. Always include a safety factor of 20–30% to accommodate unexpected loads, wear, or environmental changes.

Additionally, ensure your actuator includes:

  • Overload protection (thermal or electronic)
  • Position feedback to prevent over-travel
  • Mechanical stops or software limits

This not only extends the actuator’s lifespan but also enhances system safety and reliability.

How Can Manufacturer Tools Help in Selection?

Reputable manufacturers provide detailed technical datasheets and actuator sizing tools to help engineers make informed decisions.

Key parameters to check:

  • Rated torque or force
  • Maximum RPM or stroke speed
  • Gear ratio
  • Motor type (brushed, brushless, stepper)
  • Mounting dimensions
  • Certification standards (ATEX, IECEx, ISO)

Many companies, including Valen Tech Co., Ltd., offer online configurators or downloadable software to simulate actuator performance under specific conditions.

Can You See Real-World Application Examples?

A. Ball Valve Automation

  • Torque Requirement: 800 Nm
  • Recommended Actuator: Quarter-turn electric actuator with 1,000+ Nm output
  • Voltage: 230V AC
  • Control: Modbus RTU with position encoder
  • Mounting: ISO 5211 F07/F10 flange

B. Gate Valve Operation

  • Linear Force Needed: 15,000 N
  • Recommended Actuator: Heavy-duty linear actuator with ball screw drive
  • Duty Cycle: Continuous
  • Environment: Outdoor, wet location (IP67 rating required)
  • Control: PLC interface with soft-start feature

C. Conveyor Belt Gate Control

  • Force Needed: 2,500 N
  • Actuator Type: Medium-duty linear actuator
  • Voltage: 24V DC
  • Safety Margin: 30%
  • Features: Limit switches, manual override

What Is the Final Takeaway?

Selecting the right electric actuator based on force or torque requirements involves more than just matching numbers. It requires a thorough understanding of the application dynamics, environmental conditions, control needs, and system integration requirements.

By following a structured approach — from identifying motion type and calculating load forces to evaluating duty cycles and control compatibility — you can ensure optimal actuator performance and longevity.

At Valen Tech Co., Ltd., we offer a wide range of high-performance electric actuators designed for precision, durability, and smart connectivity. Whether you're automating valves, gates, or complex industrial systems, our team provides expert consultation and tailored solutions.

Visit www.valen-tech.com to explore our product catalog, download technical guides, or contact our engineering support team for personalized assistance.

Explore our full range of products at //www.valen-tech.com/ or contact our team for expert consultation and actuator sizing support.